Energy source apparatus

ABSTRACT

A treatment system includes a treatment tool having a heater and bipolar electrodes to grip a treatment target. An energy source apparatus is used to electrically communicate with the treatment tool. The energy output source is configured to output high-frequency electric power to the bipolar electrodes through a first circuit. A high-frequency current flows through the treatment target between the bipolar electrodes. The energy output source is configured to output heater electric power to the heater for generating heat through a second circuit. At least one processor is used to control the energy output source.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of PCT Application No. PCT/JP 2017/009277 filed on Mar. 8, 2017, which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

The technology disclosed herein relates generally to an energy source apparatus, and more particularly, some embodiments relate to an energy source apparatus for use with a treatment tool having bipolar electrodes and a heater.

DESCRIPTION OF THE RELATED ART

US Patent Application Pub. No. 2009/0248002A1 discloses a treatment tool capable of gripping a treatment target such as a biotissue or the like between a pair of grippers and an energy source apparatus for supplying the treatment tool with electric energy. In the treatment tool, each of the grippers includes an electrode and at least one of the grippers includes a heater. The energy source apparatus outputs high-frequency electric power to the electrodes, i.e., bipolar electrodes, and outputs heater electric power to the heater. Consequently, a high-frequency current flows between the electrodes through the gripped treatment target and heat generated by the heater is applied to the gripped treatment target. In other words, both the high-frequency current and the heater heat are applied to the treatment target.

According to US Patent Application Pub. No. 2009/0248002A1, the energy source apparatus detects the state of the treatment target using the high-frequency electric power. The energy source apparatus controls the output of the high-frequency electric power based on the detected state of the treatment target. While both the high-frequency current and the heat are being applied to the treatment target, the heater heat may possibly affect the detection of the state of the treatment target using the high-frequency electric power. If the heater heat affects the detection of the state using the high-frequency electric power, then the heater heat also affects the control of the output of the high-frequency electric power based on the state of the treatment target.

BRIEF SUMMARY OF EMBODIMENTS

The disclosed technology has been made in view of the foregoing.

One aspect of the disclosed technology is directed a treatment system that comprises a treatment tool having a heater and bipolar electrodes to grip a treatment target. An energy source apparatus is used to electrically communicate with the treatment tool. The energy output source is configured to output high-frequency electric power to the bipolar electrodes through a first circuit. A high-frequency current flows through the treatment target between the bipolar electrodes. The energy output source is configured to output heater electric power to the heater for generating heat through a second circuit. At least one processor is used to control the energy output source. The at least one processor is configured to control the heater for reaching a target temperature while maintaining the heater at the target temperature. The processor detects a parameter calculated based on the second circuit during the process of controlling the heater for reaching the target temperature. The processor sets a target value and/or a target trajectory for outputting the high-frequency electric power based on the parameter while the treatment target is being modified by the high-frequency current applied thereto.

Another aspect of the disclosed technology is directed to a method of operating a treatment system having a treatment tool including a heater and bipolar electrodes to grip a treatment target and an energy source apparatus used to electrically communicate with the treatment tool. The energy source apparatus comprises at least one processor used to control the energy output source by outputting high-frequency electric power to the bipolar electrodes through a first circuit. A high-frequency current is flowing through the treatment target between the bipolar electrodes. The energy output source is configured to output heater electric power to the heater for generating heat through a second circuit. Next, controlling the heater for reaching a target temperature while maintaining the heater at the target temperature. Then, detecting a parameter calculated based on the second circuit during the process of controlling the heater for reaching the target temperature. Finally, setting a target value and/or a target trajectory for outputting a high-frequency electric power based on the parameter.

BRIEF DESCRIPTION OF THE DRAWINGS

The technology disclosed herein, in accordance with one or more various embodiments, is described in detail with reference to the following figures. The drawings are provided for purposes of illustration only and merely depict typical or example embodiments of the disclosed technology. These drawings are provided to facilitate the reader's understanding of the disclosed technology and shall not be considered limiting of the breadth, scope, or applicability thereof. It should be noted that for clarity and ease of illustration these drawings are not necessarily made to scale.

FIG. 1 is a schematic view illustrating a treatment system according to a first embodiment.

FIG. 2 is a block diagram schematically illustrating an arrangement for supplying electric energy from an energy source apparatus according to the first embodiment to a treatment tool.

FIG. 3 is a flowchart of a processing sequence carried out by a processor of the energy source apparatus according to the first embodiment.

FIG. 4 is a schematic diagram illustrating an example of chronological changes in the temperature of a heater in the processing sequence carried out by the processor according to the first embodiment.

FIG. 5 is a schematic diagram illustrating an example of chronological changes in the heater electric power output from a heater power supply when the temperature of the heater changes chronologically as illustrated in FIG. 4 according to the first embodiment.

FIG. 6 is a schematic diagram illustrating an example of target trajectories for an impedance set when the temperature of the heater changes chronologically as illustrated in FIG. 4 according to the first embodiment.

FIG. 7 is a schematic diagram illustrating an example of chronological changes in the high-frequency electric power output from a high-frequency power supply when the temperature of the heater changes chronologically as illustrated in FIG. 4 according to the first embodiment.

FIG. 8 is a schematic diagram illustrating an example of voltage values of an output voltage set in a constant voltage control process for controlling the output from the high-frequency power supply when the temperature of the heater changes chronologically as illustrated in FIG. 4 according to a modification of the first embodiment.

FIG. 9A is a schematic diagram illustrating an example of target trajectories set for the output voltage from the high-frequency power supply when the temperature of the heater changes chronologically as illustrated in FIG. 4 according to another modification of the first embodiment.

FIG. 9B is a schematic diagram illustrating an example of target trajectories set for the output voltage from the high-frequency power supply when the temperature of the heater changes chronologically as illustrated in FIG. 4 according to still another modification of the first embodiment.

FIG. 10 is a flowchart of a processing sequence carried out by a processor of an energy source apparatus according to a second embodiment.

FIG. 11 is a schematic diagram illustrating an example of chronological changes in the heater electric power output from a heater power supply in the processing sequence carried out by the processor according to the second embodiment.

FIG. 12 is a schematic diagram illustrating an example, different from the example illustrated in FIG. 11, of chronological changes in the heater electric power output from the heater power supply in the processing sequence carried out by the processor according to the second embodiment.

FIG. 13 is a schematic diagram illustrating an example of target trajectories set for the output voltage from a high-frequency power supply when the heater electric power changes chronologically as illustrated in FIG. 11 according to the second embodiment.

FIG. 14 is a schematic diagram illustrating an example of target trajectories set for the output voltage from the high-frequency power supply when the heater electric power changes chronologically as illustrated in FIG. 12 according to the second embodiment.

FIG. 15 is a schematic diagram illustrating an example of chronological changes in the impedance of a treatment target in the processing sequence carried out by the processor according to the second embodiment.

FIG. 16 is a schematic diagram illustrating an example of target trajectories set for the output voltage from the high-frequency power supply when the heater electric power changes chronologically as illustrated in FIG. 11 according to a modification of the second embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In the following description, various embodiments of the technology will be described. For purposes of explanation, specific configurations and details are set forth in order to provide a thorough understanding of the embodiments. However, it will also be apparent to one skilled in the art that the technology disclosed herein may be practiced without the specific details. Furthermore, well-known features may be omitted or simplified in order not to obscure the embodiment being described.

It is an object of the embodiment to provide an energy source apparatus that appropriately detects the state of a treatment target even while outputting both high-frequency electric power and heater electric power to a treatment tool, and appropriately controls the output of the high-frequency electric power based on the state of the treatment target.

One aspect of the embodiment is directed to an energy source apparatus having an end effector capable of gripping a treatment target between a pair of grippers. The end effector is used with a treatment tool having a heater and bipolar electrodes. The energy source apparatus includes an energy output source that outputs high-frequency electric power to the bipolar electrodes thereby to cause a high-frequency current to flow through a treatment target between the bipolar electrodes. Moreover, the energy output source outputs heater electric power to the heater thereby to cause the heater to generate heat. A processor performs an output control process on the output to the heater to cause the heater to reach a target temperature and to maintain the heater at the target temperature. The processor detects a parameter related to the temperature of the heater and the output to the heater in the output control process based on the target temperature, and sets at least one of a target value and a target trajectory related to an output control process for controlling the output to the bipolar electrodes while the treatment target is being modified by the high-frequency current applied thereto, based on the detected parameter.

First Embodiment

A first embodiment of the present disclosure will be described below with reference to FIGS. 1 through 7.

FIG. 1 is a view illustrating a treatment system 1 according to the present embodiment. As illustrated in FIG. 1, the treatment system 1 includes a treatment tool 2 and an energy source apparatus 3 for supplying the treatment tool 2 with electric energy. When the treatment tool 2 is in use, the energy source apparatus 3 is used together with the treatment tool 2. The treatment tool 2 includes a shaft 5 having a longitudinal axis C as its central axis. A housing 6 that can be held is coupled to an end, i.e., proximal end, of the shaft 5 in a direction along the longitudinal axis C. An end effector 7 is disposed on the end of the shaft 5 that is opposite to the end where the housing 6 is positioned, i.e., on a distal end of the shaft 5. The housing 6 includes a grip 11 and a handle 12 mounted angularly movably thereon. When the handle 12 is angularly moved with respect to the housing 6, the handle 12 is opened or closed with respect to the grip 11.

The end effector 7 includes a pair of grippers 15 and 16. In the treatment tool 2, a movable member 13 extends along the longitudinal axis C inside or outside of the shaft 5. The movable member 13 has an end, i.e., distal end, connected to the end effector 7. The other end, i.e., proximal end, of the movable member 13 is coupled to the handle 12 in the housing 6. When the handle 12 is opened or closed with respect to the grip 11, the movable member 13 moves along the longitudinal axis C of the shaft 5, opening or closing the grippers 15 and 16. The grippers 15 and 16 are thus capable of gripping a biotissue such as a blood vessel or the like as a treatment target therebetween. According to an embodiment, one of the grippers 15 and 16 is integral with or fixed to the shaft 5, whereas the other of the grippers 15 and 16 is angularly movably mounted on a distal end of the shaft 5. According to another embodiment, both the grippers 15 and 16 are angularly movably mounted on the distal end of the shaft 5. According to an embodiment, an operating member, not illustrated, such as a rotary knob or the like, is mounted on the housing 6. When the operating member is rotated with respect to the housing 6, the shaft 5 and the end effector 7 are rotated about the longitudinal axis C with respect to the housing 6.

A cable 17 has an end connected to the housing 6. The other end of the cable 17 is separably connected to the energy source apparatus 3. The treatment system 1 includes a foot switch 18 as an operating member separate from the treatment tool 2. The foot switch 18 is electrically connected to the energy source apparatus 3. The foot switch 18 inputs an operation for causing the energy source apparatus 3 to output electric energy to the treatment tool 2. According to an embodiment, an operating button or the like that is mounted as an operating member on the housing 6 is included instead of or in addition to the foot switch 18. The energy source apparatus 3 outputs electric energy to the treatment tool 2 in response to an operation entered through the operating member.

FIG. 2 is a diagram illustrating an arrangement for supplying electric energy, i.e., high-frequency electric power P and heater electric power P′ to be described hereinafter according to the present embodiment, from the energy source apparatus 3 to the treatment tool 2. As illustrated in FIG. 2, the treatment tool 2 includes an electrode 21 on the gripper 15 and an electrode 22 on the gripper 16. The electrodes 21 and 22 are bipolar electrodes included in the end effector 7. The end effector 7 includes a heater 23 as a heat generating element disposed on at least one of the grippers 15 and 16.

The energy source apparatus 3 includes a processor, i.e., controller, 25 and a storage medium 26. The processor 25 is in the form of an integrated circuit or the like including a central processing unit (CPU), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or the like. The energy source apparatus 3 may include only one processor 25 or a plurality of processors 25. The processor 25 carries out a processing sequence according to programs stored in the processor 25 or the storage medium 26. The storage medium 26 stores processing programs used by the processor 25, parameters, functions, and tables used in operations performed by the processor 25, and so on. The processor 25 detects whether or not an operation is entered through the operating member such as the foot switch 18 or the like.

The energy source apparatus 3 includes a high-frequency power supply 31 as an energy output source. The high-frequency power supply 31 includes a waveform generator, a converting circuit, a transformer, and so on. The high-frequency power supply 31 converts electric power from a battery power supply, an outlet power supply, or the like into high-frequency electric power P. The high-frequency power supply 31 is electrically connected to the electrode 21 on the gripper 15 through an electric supply path 32. The high-frequency power supply 31 is also electrically connected to the electrode 22 on the griper 16 through an electric supply path 33. Each of the electric supply paths 32 and 33 extends in the cable 17, the housing 6, and the shaft 5. Each of the electric supply paths 32 and 33 is in the form of an electric wire or the like. The high-frequency power supply 31 is capable of outputting the converted high-frequency electric power P. While the treatment target is being gripped between the grippers 15 and 16, the high-frequency electric power P output from the high-frequency power supply 31 is supplied through the electric supply paths 32 and 33 to the electrodes 21 and 22. Therefore, a high-frequency current flows through the treatment target between the electrodes, i.e., bipolar electrodes 21 and 22. At this time, the electrodes 21 and 22 have respective potentials that are different from each other. When a high-frequency current having a certain magnitude is applied as treatment energy to the treatment target, the treatment target is modified by the heat caused by the high-frequency current. When an operation is entered through the foot switch 18 or the like, the processor 25 controls the output from the high-frequency power supply 31 to the electrodes 21 and 22 in a manner to be described hereinafter.

The electric paths through which the high-frequency electric power P is output from the high-frequency power supply 31 to the electrodes 21 and 22 include a current detecting circuit 35 and a voltage detecting circuit 36. While the high-frequency electric power P is being output from the high-frequency power supply 31, the current detecting circuit 35 detects the current value of an output current I from the high-frequency power supply 31. At the same time, the voltage detecting circuit 36 detects the voltage value of an output voltage V from the high-frequency power supply 31. An analog signal representing the current value detected by the current detecting circuit 35 and an analog signal representing the voltage value detected by the voltage detecting circuit 36 are converted into digital signals by analog-digital (A/D) converters, not illustrated, or the like. The converted digital signals are transmitted to the processor 25. The processor 25 now acquires information regarding the output current I and the output voltage V from the high-frequency power supply 31. Based on the output current I and the output voltage V that have been acquired, the processor 25 detects impedances of the electric paths through which the high-frequency electric power P is output from the high-frequency power supply 31 to the electrodes 21 and 22. Based on the impedances of the electric paths for the high-frequency electric power P, the processor 25 detects an impedance Z of the gripped treatment target, i.e., a tissue impedance. Based on the output current I and the output voltage V that have been acquired, the processor 25 also detects an electric power value of the high-frequency electric power P, i.e., an electric power value of the output electric power from the high-frequency power supply 31 to the electrodes 21 and 22. The processor 25 controls the output from the high-frequency power supply 31 using the output current I and the output voltage V that have been acquired, and the impedance Z and the high-frequency electric power P that have been detected, in a manner to be described hereinafter.

The energy source apparatus 3 includes a heater power supply 41 as an energy output source. The heater power supply 41 includes a converting circuit, a transformer, and so on. The heater power supply 41 converts electric power from a battery power supply, an outlet power supply, or the like into heater electric power P′. The heater power supply 41 is electrically connected to the heater 23 through electric supply paths 42 and 43. Each of the electric supply paths 42 and 43 extends in the cable 17, the housing 6, and the shaft 5. Each of the electric supply paths 42 and 43 is in the form of an electric wire or the like. The heater power supply 41 is capable of outputting the converted heater electric power P′. The heater electric power P′ that is output is direct current (DC) electric power or alternate current (AC) electric power. When the heater electric power P′ output from the heater power supply 41 is supplied through the electric supply paths 42 and 43 to the heater 23, the heater 23 generates heat. While the treatment target is being gripped between the grippers 15 and 16, the heat generated by the heater 23 is applied to the treatment target. When a certain amount of heater heat is applied as treatment energy to the treatment target, the treatment target is modified. When an operation is entered through the foot switch 18 or the like, the processor 25 controls the output from the heater power supply 41 to the heater 23 in a manner to be described hereinafter.

The electric paths through which the heater electric power P′ is output from the heater power supply 41 to the heater 23 include a current detecting circuit 45 and a voltage detecting circuit 46. While the heater electric power P′ is being output from the heater power supply 41, the current detecting circuit 45 detects the current value of an output current I′ from the heater power supply 41. At the same time, the voltage detecting circuit 46 detects the voltage value of an output voltage V′ from the heater power supply 41. An analog signal representing the current value detected by the current detecting circuit 45 and an analog signal representing the voltage value detected by the voltage detecting circuit 46 are converted into digital signals by A/D converters, not illustrated, or the like. The converted digital signals are transmitted to the processor 25. The processor 25 now acquires information regarding the output current I′ and the output voltage V′ from the heater power supply 41. Based on the output current I′ and the output voltage V′ that have been acquired, the processor 25 detects impedances of the electric paths through which the heater electric power P′ is output from the heater power supply 41 to the heater 23. Based on the impedances of the electric paths for the heater electric power P′, the processor 25 detects a resistance R of the heater 23. The resistance R of the heater 23 varies depending on a temperature T of the heater 23. The storage medium 26 or the like stores a function, a table, or the like that represents the relationship between the temperature T and the resistance R of the heater 23. Based on the detected resistance R and the stored relationship between the temperature T and the resistance R, the processor 25 detects the temperature T of the heater 23. Based on the output current I′ and the output voltage V′ that have been acquired, the processor 25 also detects an electric power value of the heater electric power P′, i.e., an electric power value of the output electric power from the heater power supply 41 to the heater 23. The processor 25 controls the output from the high-frequency power supply 31 and the output from the heater power supply 41 using the output current I′ and the output voltage V′ that have been acquired and the temperature T, i.e., the resistance R, and the heater electric power P′ that have been detected, in a manner to be described hereinafter.

Next, operation and advantages of the energy source apparatus 3 and the treatment system 1 will be described below. For performing a treatment using the treatment system 1, the treatment tool 2 is connected through the cable 17 to the energy source apparatus 3. The surgeon holds the housing 6 and inserts the end effector 7 into a body cavity such as an abdominal cavity or the like. While a treatment target such as a biotissue or the like is being positioned between the grippers 15 and 16, the surgeon closes the handle 12 on the grip 11. The grippers 15 and 16 are now closed, gripping the treatment target therebetween. When the surgeon enters an operation through the operating member such as the foot switch 18 or the like while the treatment target is being gripped, the output from the high-frequency power supply 31 to the electrodes 21 and 22 and the output from the heater power supply 41 to the heater 23 are controlled. When the high-frequency electric power P is supplied to the electrodes 21 and 22, a high-frequency current flows through the treatment target as described hereinbefore. When the heater electric power P′ is supplied to the heater 23, heat generated by the heater 23 is applied to the treatment target. The treatment target is treating using the high-frequency current and the heater heat as treatment energy.

FIG. 3 is a flowchart of a processing sequence carried out by the processor 25 of the energy source apparatus 3. As illustrated in FIG. 3, the processor 25 determines whether or not an operation is entered through the operating member such as the foot switch 18 or the like, i.e., whether the entry of an operation is ON or OFF (S101). If an operation is not entered (S101—No), then processing returns to S101. In other words, the processor 25 waits until an operation is entered through the operating member. If an operation is entered through the operating member (S101—Yes), then the processor 25 starts to output the high-frequency electric power P from the high-frequency power supply 31 to the electrodes 21 and 22 and also starts to output the heater electric power P′ from the heater power supply 41 to the heater 23. According to the present embodiment, when the high-frequency electric power P starts to be output, the processor 25 outputs the high-frequency electric power P from the high-frequency power supply 31 at an electric power value that is constant as a fixed value P0 (S102). At this time, the output current I and the output voltage V from the high-frequency power supply 31 are adjusted to keep the electric power value of the output electric power from the high-frequency power supply 31 constant as the fixed value P0.

When the heater electric power P′ starts to be output from the heater power supply 41, the processor 25 performs a proportional-integral-derivative (PID) control process for a target temperature T0 on the output from the heater power supply 41 to the heater 23 (S103). Specifically, an output control process is carried out on the output to the heater 23 for causing the temperature T of the heater 23 to reach the target temperature T0 while maintaining the temperature T of the heater 23 at the target temperature T0. According to the PID control process for the target temperature T0, the processor 25 detects the resistance R of the heater 23 based on the output current I′ and the output voltage V′ from the heater power supply 41 and detects the temperature T of the heater 23 based on the detected resistance R, as described hereinbefore. Then, the processor 25 adjusts the output electric power, i.e., the heater electric power P′, the output current I′, and the output voltage V′ to the heater 23, based on the temperature deviation between the target temperature T0 and the temperature T of the heater 23, a time integral value of the temperature deviation, i.e., an integrated value of the temperature deviation, and a time differential value of the temperature deviation, i.e., a time rate of change of the temperature deviation, causing the temperature T to reach the target temperature T0 and maintaining the temperature T at the target temperature T0. For example, if the temperature deviation between the target temperature T0 and the temperature T is large, then the processor 25 causes the heater power supply 41 to output the heater electric power P′ at a large electric power value. If the temperature deviation between the target temperature T0 and the temperature T is small, and the temperature deviation is zero, then the processor 25 causes the heater power supply 41 to output the heater electric power P′ at a small electric power value.

In an output control process for controlling the output from the heater power supply 41 to the heater 23 based on the target temperature T0, the processor 25 detects a chronological rate α of rise of the temperature T up to the target temperature T0 as a parameter related to the temperature T of the heater 23 (S104). The rate α of rise of the temperature T varies depending on a tissue volume of the treatment target including the thickness of a blood vessel, etc., the degree of wetness of the treatment target, and so on. In other words, the rate α of rise, i.e., the speed of rise, varies depending on the state of the treatment target including a thermal load on the treatment target. The thermal load on the treatment target represents how difficult it is for the temperature of the treatment target to rise. Providing identical amounts of heat are applied to the treatment target, the temperature of the treatment target is more difficult to rise under a larger thermal load. The processor 25 sets a chronological rate β(α) of increase of the impedance Z as a target value with respect to an output control process for controlling the output from the high-frequency power supply 31 to the electrodes 21 and 22, based on the rate α of rise detected as a parameter (S105). At this time, the rate β(α) of increase is calculated using the detected rate α of rise and a function or table, stored in the storage medium 26 or the like, representing the relationship between rates α of rise of the temperature T and rates β of increase of the impedance Z. The processor 25 sets a target trajectory for the impedance Z as a target trajectory with respect to the output control process for controlling the output from the high-frequency power supply 31 (S106). At this time, the target trajectory is set such that the impedance Z increases chronologically constantly at the set rate β(α) of increase. According to the present embodiment, the rate β(α) of increase of the impedance Z is set such that the smaller the rate α of rise of the temperature T is, the larger the rate β(α) of increase of the impedance Z. Therefore, the smaller the rate α of rise of the temperature T, the processor 25 sets the gradient of the target trajectory for the impedance Z to a larger value, and sets the value on the target trajectory to a larger value at each point of time. After the rate α of rise of the temperature T has been calculated and the rate β(α) of increase of the impedance Z and the target trajectory have been set, the processor 25 performs the above PID control process for the target temperature T0 on the output from the heater power supply 41 to the heater 23 (S107).

When the rate α of rise of the temperature T is calculated and the rate β(α) of increase of the impedance Z and the target trajectory are set, the processor 25 switches the output from the high-frequency power supply 31 in a manner to have the impedance Z vary along the target trajectory. In other words, the processor 25 controls the output of the high-frequency electric power P from the high-frequency power supply 31 to the electrodes 21 and 22 in a manner to have the impedance Z vary chronologically along the target trajectory for the set rate β(α) of increase (S108). At this time, the output electric power from the high-frequency power supply 31, i.e., the high-frequency electric power P, the output current I, and the output voltage V are adjusted in a manner to have the impedance Z increase at a constant rate β(α) of increase. While the output of the high-frequency electric power P is being controlled based on the target trajectory for the impedance Z, the treatment target is modified by the high-frequency current applied thereto. If the high-frequency current is continuously applied to the treatment target that has been dehydrated to a certain extent, then the impedance Z increases chronologically due to the heat caused by the high-frequency current. According to the present embodiment, moreover, at a point of time upon elapse of a certain time from the start of the output control process for controlling the output from the high-frequency power supply 31 based on the target trajectory for the impedance Z, the treatment target is dehydrated to a certain extent due to the heater heat and the heat caused by the high-frequency current. Therefore, after the point of time upon elapse of the certain period of time from the start of the output control process for controlling the output from the high-frequency power supply 31 based on the target trajectory for the impedance Z, the impedance Z increases chronologically due to the continuously applied high-frequency current.

While the output of the high-frequency electric power P is being controlled based on the target trajectory for the impedance Z, the processor 25 detects whether or not an output time Q of the high-frequency electric power P is equal to or larger than a threshold value Qth (S109). According to an embodiment, the output time Q is detected from the time, used as a reference, when the output control process for controlling the output from the high-frequency power supply 31 based on the target trajectory for the impedance Z is started. According to another embodiment, the output time Q is detected from the time, used as a reference, when the high-frequency electric power P starts to be output. In other words, the processor 25 detects the output time Q from a certain point of time, used as a reference, after the high-frequency power supply 31 starts to output the high-frequency electric power P. According to the present embodiment, the processor 25 sets the threshold value Qth to a fixed value Qth0. If the output time Q of the high-frequency electric power P is shorter than the threshold value Qth (S109—No), then processing goes back to step S107. Then, the steps from S107 are successively carried out. Therefore, the processor 25 continues the output from the high-frequency power supply 31 to the electrodes, i.e., bipolar electrodes 21 and 22, continuously modifying the treatment target with the application of the high-frequency current thereto. If the output time Q of the high-frequency electric power P is equal to or larger than the threshold value Qth (S109—Yes), then the processor 25 stops the output from the high-frequency power supply 31 to the electrodes 21 and 22 (S110). At this time, the processor 25 may stop the output from the heater power supply 41 to the heater 23 in response to the stoppage of the output to the electrodes 21 and 22, or may continue the output from the heater power supply 41 to the heater 23. If the output to the heater 23 is continued, then the processor 25 stops the output from the heater power supply 41 upon elapse of a certain time from the stoppage of the output to the electrodes 21 and 22 or based on an operation entered by the surgeon or the like. In case the output to the heater 23 is continued, the processor 25 does not need to continue the PID control process for the target temperature T0. For example, in response to the stoppage of the output to the electrodes 21 and 22, the processor 25 may control the output of the heater electric power P′ to the heater 23 to lower the temperature T of the heater 23 to a target temperature Ta0 lower than the target temperature T0 and maintain the temperature T of the heater 23 at the target temperature Ta0. In this case, the target temperature Ta0 is set to a temperature low enough not to modify the treatment target, for example.

FIG. 4 illustrates an example of chronological changes in the temperature T of the heater 23 in the processing sequence carried out by the processor 25 as described hereinbefore. FIG. 5 illustrates an example of chronological changes in the heater electric power P′ output from the heater power supply 41 to the heater 23 when the temperature T of the heater 23 changes chronologically as illustrated in FIG. 4. FIG. 6 illustrates an example of target trajectories for the impedance Z set when the temperature T of the heater 23 changes chronologically as illustrated in FIG. 4. FIG. 7 illustrates an example of chronological changes in the high-frequency electric power P output from the high-frequency power supply 31 to the electrodes 21 and 22 when the temperature T of the heater 23 changes chronologically as illustrated in FIG. 4. In each of FIGS. 4 through 7, a horizontal axis represents time t from the start, used as a reference, of the output from the heater power supply 41. In FIG. 4, a vertical axis represents the temperature T of the heater 23. In FIG. 5, a vertical axis represents the heater electric power P′. In FIG. 6, a vertical axis represents the impedance Z of the treatment target. In FIG. 7, a vertical axis represents the high-frequency electric power P. Each of FIGS. 4 through 7 illustrates the chronological changes in three states, i.e., tissue states, X1 through X3. The states X1 through X3 indicate thermal loads on the treatment target that are different from each other due to the tissue volume of the treatment target and/or the degree of wetness of the treatment target. In the state X1, the tissue volume of the treatment target is smaller because the blood vessel as the treatment target is thin, etc., and/or the treatment target is drier, than in the state X2. Therefore, the thermal load on the treatment target is smaller in the state X1 than in the state X2. In the state X3, the tissue volume of the treatment target is larger because the blood vessel as the treatment target is thick, etc., and/or the treatment target is wetter, than in the state X2. Therefore, the thermal load on the treatment target is larger in the state X3 than in the state X2. In each of FIGS. 4 through 7, the chronological changes in the state X1 are indicated by the solid-line curve, the chronological changes in the state X2 by the dot-and-dash-line curve, and the chronological changes in the state X3 by the broken-line curve.

When the PID control process is performed on the output from the heater power supply 41 for the target temperature T0, as described hereinbefore, the larger the thermal load on the treatment target, the smaller the rate α of rise of the temperature T up to the target temperature T0. In the examples illustrated in FIGS. 4 through 7, actually, the rate α1 of rise of the temperature T in the state X1 is larger than the rate α2 of rise of the temperature T in the state X2, and the rate α3 of rise of the temperature T in the state X3 is smaller than the rate α2 of rise of the temperature T in the state X2.

When the PID control process is performed for the target temperature T0, until the temperature T becomes close to the target temperature T0 to a certain extent after the heater electric power P′ has started to be output, since the temperature deviation between the target temperature T0 and the temperature T is large, the processor 25 increases the output from the heater power supply 41. Consequently, the heater electric power P′ increases chronologically until the temperature T becomes close to the target temperature T0 to a certain extent. When the temperature T becomes close to the target temperature T0 to a certain extent, the temperature deviation between the target temperature T0 and the temperature T becomes small. It is also necessary to prevent the temperature T from overshooting the target temperature T0. Therefore, when the temperature T becomes close to the target temperature T0 to a certain extent, the processor 25 reduces the output from the heater power supply 41. Consequently, when the temperature T becomes close to the target temperature T0 to a certain extent, the heater electric power P′ decreases chronologically. As the heater electric power P′ changes chronologically as described hereinbefore, until the temperature T reaches the target temperature T0 after the temperature T has become close to the target temperature T0 to a certain extent, e.g., immediately before the temperature T reaches the target temperature T0, the heater electric power P′ becomes peak electric power P′p. At the time the heater electric power P′ has become the peak electric power P′p, the heater electric power P′ switches from a chronologically increasing state to a chronologically decreasing state.

When the PID control process is performed on the output from the heater power supply 41 for the target temperature T0, as described hereinbefore, the larger the thermal load on the treatment target, the higher the output from the heater power supply 41. Therefore, the larger the thermal load on the treatment target, the larger the peak electric power P′p of the heater electric power P. In the examples illustrated in FIGS. 4 through 7, actually, the peak electric power P′p1 of the heater electric power P′ in the state X1 is smaller than the peak electric power P′p2 of the heater electric power P′ in the state X2, and the peak electric power P′p3 of the heater electric power P′ in the state X3 is larger than the peak electric power P′p2 of the heater electric power P′ in the state X2. Prior to the point of time at which the heater electric power P′ has decreased from the peak electric power P′p to a certain extent, the larger the thermal load on the treatment target, the larger an integrated value W′ of the heater electric power P′ between two points of time, as is the case with the peak electric power P′p. For example, the larger the thermal load on the treatment target, the larger the integrated value of the heater electric power P′ until it reaches the peak electric power P′p after it has started to be output. Inasmuch as the larger the thermal load on the treatment target, the smaller the rate α of rise of the temperature T, a time Y required for the heater electric power P′ to reach the peak electric power P′p after it has started to be output is long. In the examples illustrated in FIGS. 4 through 7, actually, a time Y1 required for the heater electric power P′ to reach the peak electric power P′p1 in the state X1 is shorter than a time Y2 required for the heater electric power P′ to reach the peak electric power P′p2 in the state X2, and a time Y3 required for the heater electric power P′ to reach the peak electric power P′p3 in the state X3 is longer than the time Y2 required for the heater electric power P′ to reach the peak electric power P′p2 in the state X2.

In case the thermal load on the treatment target is small because the tissue volume is small, etc., the temperature T of the heater 23 rises even though the heater electric power P′ that is output is small to a certain degree. Therefore, in case the thermal load on the treatment target is small, the heater electric power P′ increases gradually until it reaches the peak electric power P′p immediately after it has started to be output according to the PID control process for the target temperature T0. Even after the heater electric power P′ has reached the peak electric power P′p, the heater electric power P′ decreases gradually. On the other hand, in case the thermal load on the treatment target is large because the tissue volume is large, etc., it is difficult for the temperature T of the heater 23 to rise unless the heater electric power P′ that is output is increased to a certain extent. Therefore, in case the thermal load on the treatment target is large, the heater electric power P′ increases quickly until it reaches the peak electric power P′p immediately after it has started to be output according to the PID control process for the target temperature T0. After the heater electric power P′ has reached the peak electric power P′p, the processor 25 quickly reduces the heater electric power P′ in order to prevent the temperature T from overshooting the target temperature T0. As the heater electric power P′ varies depending on the thermal load on the treatment target, as described hereinbefore, the larger the thermal load on the treatment target, the larger a rate γ of increase of the heater electric power P′ up to the peak electric power P′p. Furthermore, the larger the thermal load on the treatment target, the larger a rate ε of reduction of the heater electric power P′ after having reached the peak electric power P′p. In the examples illustrated in FIGS. 4 through 7, actually, the rate γ1 of increase of the heater electric power P′ in the state X1 is smaller than the rate γ2 of increase of the heater electric power P′ in the state X2, and the rate γ3 of increase of the heater electric power P′ in the state X3 is larger than the rate γ2 of increase of the heater electric power P′ in the state X2. The rate ε1 of reduction of the heater electric power P′ in the state X1 is smaller than the rate ε2 of reduction of the heater electric power P′ in the state X2, and the rate ε3 of reduction of the heater electric power P′ in the state X3 is larger than the rate ε2 of reduction of the heater electric power P′ in the state X2.

Moreover, since the larger the thermal load on the treatment target, the larger the rate α of rise of the temperature T, the processor 25 sets the rate β of increase of the impedance Z as the target value with respect to the output control process for controlling the output to the electrodes 21 and 22, to a large value. Actually, the rate β(α1) of increase of the impedance Z set in the state X1 is smaller than the rate β(α2) of increase of the impedance Z set in the state X2. The rate β(α3) of increase of the impedance Z set in the state X3 is larger than the rate β(α2) of increase of the impedance Z set in the state X2. Furthermore, since the larger the thermal load on the treatment target, the larger the rate β of increase of the impedance Z is set, the processor 25 sets the value of the impedance Z on the target trajectory at each point of time until the output of the high-frequency electric power P is stopped, to a large value. Actually, at each point of time until the output time Q of the high-frequency electric power P reaches the threshold value Qth, i.e., Qth0 according to the present embodiment, the value on the target trajectory set in the state X1 is smaller than the value on the target trajectory set in the state X2. At each point of time until the output time Q of the high-frequency electric power P reaches the threshold value Qth, the value on the target trajectory set in the state X3 is larger than the value on the target trajectory set in the state X2. When the output of the high-frequency electric power P is stopped, i.e., when the output time Q reaches the threshold value Qth, the value Z1 of the impedance Z according to the target trajectory set in the state X1 is smaller than the value Z2 of the impedance Z according to the target trajectory set in the state X2. When the output of the high-frequency electric power P is stopped, the value Z3 of the impedance Z according to the target trajectory set in the state X3 is smaller than the value Z2 of the impedance Z according to the target trajectory set in the state X2.

According to the present embodiment, as described hereinbefore, when the rate α of rise of the temperature T is detected, the processor 25 performs the output control process for controlling the output of the high-frequency electric power P based on the target trajectory where the impedance Z increases chronologically at the set rate β of increase. In the output control process for controlling the output of the high-frequency electric power P based on the target trajectory for the impedance Z, the larger the rate β of increase for the impedance Z, the larger the high-frequency electric power P that is output. According to the present embodiment, inasmuch as the larger the thermal load on the treatment target, the larger the rate β of increase of the impedance Z is set, the high-frequency electric power P that is output is large. Therefore, In the output control process for controlling the output of the high-frequency electric power P based on the target trajectory for the impedance Z, the larger the thermal load on the treatment target, the larger the high-frequency current flowing through the treatment target. In the examples illustrated in FIGS. 4 through 7, actually, in the output control process for controlling the output of the high-frequency electric power P based on the target trajectory for the impedance Z, the high-frequency electric power P that is output is smaller in the state X1 than in the state X2, and the high-frequency electric power P that is output is larger in the state X3 than in the state X2. In the output control process for controlling the output of the high-frequency electric power P based on the target trajectory for the impedance Z, the high-frequency electric power P that is output increases chronologically while the impedance Z is being low. When the impedance Z rises to a certain extent, the high-frequency electric power P that is output switches from a chronologically increasing state to a chronologically decreasing state. Until the output of the high-frequency electric power P is stopped, the high-frequency electric power P decreases chronologically. In the examples illustrated in FIGS. 4 through 7, before the rate α of rise is detected, the output from the high-frequency power supply 31 is controlled to keep the electric power value of the high-frequency electric power P constant as the fixed value P0 in either one of the states X1 through X3.

According to the present embodiment, as described hereinbefore, the control process for controlling the output to the heater 23 is carried out to cause the heater 23 to reach the target temperature T0 and to keep the heater 23 at the target temperature T0. In the control process based on the target temperature T0, the rate α of rise until the temperature T reaches the target temperature T0 is detected as a parameter related to the temperature T of the heater 23. Since the rate α of rise of the temperature T varies depending on the tissue volume and the degree of wetness of the treatment target, as described hereinbefore, the rate α of rise of the temperature T varies depending on the state of the treatment target including the thermal load on the treatment target. Consequently, even while the treatment tool 2 is being supplied with both the high-frequency electric power P and the heater electric power P′, the state of the treatment tool can appropriately be detected by detecting the rate α of rise.

According to the present embodiment, furthermore, in the output control process for controlling the output from the high-frequency power supply 31 while the treatment target is being modified by the high-frequency current, the rate β(α) of increase of the impedance Z as a target value and the target trajectory for the impedance Z are set based on the detected rate α of rise of the temperature T. Since the rate β(α) of increase of the impedance Z and the target trajectory for the impedance Z are set based on the rate α of rise, the rate β(α) of increase is set to an appropriate value corresponding to the state of the treatment target, and the target trajectory for the impedance Z is set to an appropriate trajectory corresponding to the state of the treatment target. By controlling the output of the high-frequency electric power P based on the rate β(α) of increase of the impedance Z and the target trajectory that have been set, therefore, the high-frequency power supply 31 outputs the high-frequency electric power P appropriately depending on the state of the treatment target, appropriately applying the high-frequency current to the treatment target depending on the state of the treatment target. According to the present embodiment, therefore, even while the treatment tool 2 is being supplied with both the high-frequency electric power P and the heater electric power P′, the output of the high-frequency electric power P is appropriately controlled based on the state of the treatment target.

Modifications of the First Embodiment

According to the first embodiment, in the output control process for controlling the output from the heater power supply 41 based on the target temperature T0, the rate α of rise of the temperature T is detected, and the rate β of increase of the impedance Z and the target trajectory for the impedance Z, which are target values with respect to the output control process for controlling the output to the electrodes 21 and 22, are set based on the detected rate α of rise. However, the present disclosure is not limited to such details. According to a modification, in the output control process for controlling the output from the heater power supply 41 based on the target temperature T0, the processor 25 detects either one of the peak electric power P′p of the heater electric power P′, the time Y required for the heater electric power P′ to reach the peak electric power P′p, the rate γ of increase of the heater electric power P′ up to the peak electric power P′p, the rate of reduction of the heater electric power P′ after having reached the peak electric power P′p, and the integrated value W′ of the heater electric power P′ as a parameter related to the output to the heater 23, instead of carrying out the processing of step S104 for detecting the rate α of rise of the temperature T. The integrated value W′ of the heater electric power P′ may be either one of an integrated value between two points of time until the peak electric power P′p is reached, an integrated value between two points of time including the peak electric power P′p, and an integrated value between two points of time after the peak electric power P′p has been reached. The processor 25 then sets the rate β of increase of the impedance Z as a target value related to the output control process for controlling the output from the high-frequency power supply 31 to the electrodes 21 and 22, based on the above parameter, i.e., either one of P′p, Y, γ, ε, and W′, related to the detected output to the heater 23, instead of carrying out the processing of step S105. Then, in the same manner as the processing of step S106, the processor 25 sets the target trajectory for the impedance Z as a target trajectory related to the output control process for controlling the output from the high-frequency power supply 31 to the electrodes 21 and 22, based on the set rate β of increase of the impedance Z.

As described hereinbefore, since each of the peak electric power P′p, the reaching time Y, the rate γ of increase, the rate ε of reduction, and the integrated value W′ varies depending on the tissue volume of the treatment target, the degree of wetness of the treatment target, etc., ease of those parameters varies depending on the state of the treatment target including the thermal load on the treatment target. However, as described hereinbefore, the larger the thermal load on the treatment target, the larger each of the parameters, i.e., P′p, Y, γ, ε, and W′. According to the present modification, therefore, the larger the parameter, i.e., either one of P′p, Y, γ, ε, and W′, related to the detected output to the heater 23, the processor 25 sets the rate β of increase of the impedance Z to a larger value. Consequently, the larger the parameter, i.e., either one of P′p, Y, γ, ε, and W′, related to the detected output to the heater 23, the processor 25 sets the gradient of the target trajectory for the impedance Z to a larger value, and sets the value on the target trajectory for the impedance Z to a larger value at each point of time.

According to the present modification, by detecting the parameter, i.e., either one of P′p, Y, γ, ε, and W′, related to the output to the heater 23, the state of the treatment target is appropriately detected even while the treatment tool 2 is being supplied with both the high-frequency electric power P and the heater electric power P′. Furthermore, as the rate β of increase of the impedance Z and the target trajectory for the impedance Z are set based on the parameter, i.e., either one of P′p, Y, γ, ε, and W′, the rate β of increase is set to an appropriate value corresponding to the state of the treatment target, and the target trajectory for the impedance Z is set to an appropriate trajectory corresponding to the state of the treatment target. Thus, by controlling the output of the high-frequency electric power P based on the set rate β of increase of the impedance Z and the set target trajectory for the impedance Z, the high-frequency electric power P is appropriately output by the high-frequency power supply 31 depending on the state of the treatment target, and the high-frequency current is appropriately applied to the treatment target depending on the state of the treatment target. According to the present modification, therefore, while the treatment tool 2 is being supplied with both the high-frequency electric power P and the heater electric power P′, the output of the high-frequency electric power P is appropriately controlled based on the state of the treatment target.

According to a modification, in the output control process for controlling the output from the heater power supply 41 based on the target temperature T0, the processor 25 detects the parameter, i.e., a, related to the temperature T of the heater 23 and a plurality of ones of the parameters, i.e., P′p, Y, γ, ε, and W′, related to the output to the heater 23. Then, the processor 25 sets the rate β of increase of the impedance Z and the target trajectory for the impedance Z, which are target values with respect to the output control process for controlling the output from the high-frequency power supply 31 to the electrodes 21 and 22, based on the detected parameters, i.e., two or more of α, P′p, Y, γ, ε, and W′.

According to a modification, the processor 25 sets the rate β of increase of the impedance Z and the target trajectory for the impedance Z based on the impedance Z before the parameter, i.e., either one of α, P′p, Y, γ, ε, and W′, is detected, in addition to the parameter, i.e., either one of α, P′p, Y, γ, ε, and W′. According to the present modification, the processor 25 detects the impedance Z based on the output from the high-frequency power supply 31 before the parameter, i.e., either one of α, P′p, Y, γ, ε, and W′, is detected. At this time, the processor 25 detects an initial value Ze of the impedance Z at the same time as or immediately after the start of the output from the high-frequency power supply 31, and/or a chronological change of the impedance Z from the initial value Ze until the parameter, i.e., either one of α, P′p, Y, γ, ε, and W′, is detected. When the rate β of increase of the impedance Z and the target trajectory for the impedance Z are to be set based on the rate α of rise of the temperature T and the chronological change of the impedance Z, for example, the rate β of increase of the impedance Z and the target trajectory for the impedance Z that are to be set are different if the impedance varies differently before the parameter, i.e., either one of α, P′p, Y, γ, ε, and W′, is detected even though the rate α of rise remains the same.

According to the embodiment described hereinbefore, etc., the output control process for controlling the output from the high-frequency power supply 31 based on the target trajectory for the impedance Z is carried out after the parameter, i.e., either one of α, P′p, Y, γ, ε, and W′, is detected. However, the present disclosure is not limited to such details. According to a modification, when the parameter, i.e., either one of α, P′p, Y, γ, ε, and W′, is detected, the processor 25 carries out a constant voltage control process for keeping the output voltage V at a constant voltage value Va with respect to the output from the high-frequency power supply 31, instead of carrying out the processing of step S108. According to the present modification, the processor 25 sets the voltage value Va of the output voltage V as a target value with respect to the constant voltage control process for controlling the output from the high-frequency power supply 31, based on the detected parameter, i.e., either one of α, P′p, Y, γ, ε, and W′, instead of carrying out the processing of steps S105 and S106. At this time, the larger the thermal load on the treatment target, the processor 25 sets the voltage value Va to a larger value. For example, if the rate α of rise of the temperature T is to be detected as a parameter related to the temperature T, then the smaller the rate α of rise, the processor 25 sets the voltage value Va as a target value to a larger value. If the peak electric power P′p of the heater electric power P′ is to be detected as a parameter related to the output to the heater 23, then the larger the peak electric power P′p, the processor 25 sets the voltage value Va to a larger value.

FIG. 8 illustrates an example of voltage values Va of the output voltage V set in the constant voltage control process for controlling the output from the high-frequency power supply 31 when the temperature T of the heater 23 changes chronologically as illustrated in FIG. 4, i.e., when the heater electric power P′ output to the heater 23 changes chronologically as illustrated in FIG. 5, according to the present modification. In FIG. 8, a horizontal axis represents time t from the start, used as a reference, of the output from the heater power supply 41, and a vertical axis the output voltage V from the high-frequency power supply 31. FIG. 8 illustrates voltages Va set as target values for the three states, i.e., tissue states, X1 through X3. In FIG. 8, the voltage Va for the state X1 is indicated by the solid-line curve, the voltage Va for the state X2 by the dot-and-dash-line curve, and the voltage Va for the state X3 by the broken-line curve. Since the thermal load on the treatment target is smaller in the state X1 than in the state X2, as described hereinbefore, the voltage value Va1 set in the constant voltage control process for the state X1 is smaller than the voltage value Va2 set in the constant voltage control process for the state X2. Moreover, since the thermal load on the treatment target is larger in the state X3 than in the state X2, the voltage value Va3 set in the constant voltage control process for the state X3 is larger than the voltage value Va2 set in the constant voltage control process for the state X2.

According to the present modification, inasmuch as the voltage value Va of the output voltage V from the high-frequency power supply 31 in the constant voltage control process is set based on the parameter, i.e., either one of α, P′p, Y, γ, ε, and W′, the voltage value Va is set to an appropriate value corresponding to the state of the treatment target. Accordingly, since the constant voltage control process is performed on the output from high-frequency power supply 31 based on the voltage value Va set as a target value, the appropriate output is produced from the high-frequency power supply 31 depending on the state of the treatment target, applying the appropriate high-frequency current to the treatment target depending on the state of the treatment target, also according to the present modification. According to the present modification, therefore, while the treatment tool 2 is being supplied with both the high-frequency electric power P and the heater electric power P′, the output from the high-frequency power supply 31 is appropriately controlled based on the state of the treatment target.

According to a modification, the processor 25 performs, on the output from the high-frequency power supply 31, a constant power control process for keeping the output electric power from the high-frequency power supply 31, i.e., the high-frequency electric power P, at a constant electric power value Pa, or a constant current control process for keeping the output current I therefrom at a constant current value Ia, rather than performing the constant voltage control process described hereinbefore. For performing the constant power control process, the processor 25 sets the electric power value Pa based on the detected parameter, i.e., either one of α, P′p, Y, γ, ε, and W′. At this time, the larger the thermal load on the treatment target, the processor 25 sets the electric power value Pa to a larger value. Similarly, for performing the constant current control process, the processor 25 sets the current value Ia based on the detected parameter, i.e., either one of α, P′p, Y, γ, ε, and W′. At this time, the larger the thermal load on the treatment target, the processor 25 sets the current value Ia to a larger value. When either one of the constant voltage control process, the constant power control process, and the constant current control process is performed, at a point of time upon elapse of a certain time from the start of either one of the constant voltage control process, the constant power control process, and the constant current control process described hereinbefore, the treatment target is dehydrated to a certain extent. Therefore, after the point of time upon elapse of the certain period of time from the start of either one of the constant voltage control process, the constant power control process, and the constant current control process, the impedance Z increases chronologically due to the continuously applied high-frequency current.

According to a modification, after the parameter, i.e., either one of α, P′p, Y, γ, ε, and W′, has been detected, the processor 25 switches between the constant voltage control process, the constant power control process, and the constant current control process based on the impedance Z. In this case, the processor 25 switches between the constant voltage control process, the constant power control process, and the constant current control process based on a switching valve Zs1 and a switching value Zs2 larger than the switching value Zs1. For example, if the impedance Z is smaller than the switching value Zs1, then the processor 25 carries out the above constant current control process on the output from the high-frequency power supply 31. If the impedance Z is equal to or larger than the switching value Zs1 and smaller than the switching value Zs2, then the processor 25 carries out the above constant power control process on the output from the high-frequency power supply 31. If the impedance Z is equal to or larger than the switching value Zs2, then the processor 25 carries out the above constant voltage control process on the output from the high-frequency power supply 31. According to the present modification, as described hereinbefore, the voltage value Va for the constant voltage control process, the electric power value Pa for the constant power control process, and the current value Ia for the constant current control process are set based on the detected parameter, i.e., either one of α, P′p, Y, γ, ε, and W′. Therefore, the larger the thermal load on the treatment target, the processor 25 sets each of the voltage value Va, the electric power value Pa, and the current value Ia to a larger value.

According to a modification, the processor 25 sets a chronological rate ηa of increase, i.e., rate of change, of the output voltage V as a target value for the output control process for controlling the output from the high-frequency power supply 31 based on the detected parameter, i.e., either one of α, P′p, Y, γ, ε, and W′, instead of performing the processing of S105. Then, the processor 25 sets a target trajectory for the set output voltage V for the output control process for controlling the output from the high-frequency power supply 31 based on the set rate ηa of increase of the output voltage V, instead of performing the processing of S106. According to the set target trajectory, the output voltage V increases chronologically constantly at the set rate ηa of increase. Then, the processor 25 controls the output from the high-frequency power supply 31 to cause the output voltage V to change along the target trajectory, instead of performing the processing of S108. According to the present modification, the larger the thermal load on the treatment target, the processor 25 sets the rate ηa of increase as a target value to a larger value. Therefore, the larger the thermal load on the treatment target, the processor 25 sets the gradient of the target trajectory for the output voltage V to a larger value, and sets the value of the output voltage V on the target trajectory to a larger value at each point of time.

FIG. 9A illustrates an example of target trajectories set for the output voltage V from the high-frequency power supply 31 when the temperature T of the heater 23 changes chronologically as illustrated in FIG. 4, i.e., when the heater electric power P′ output to the heater 23 changes chronologically as illustrated in FIG. 5, according to the present modification. In FIG. 9A, a horizontal axis represents time t from the start, used as a reference, of the output from the heater power supply 41, and a vertical axis the output voltage V from the high-frequency power supply 31. FIG. 9A illustrates the target trajectories in the above three states, i.e., tissue states, X1 through X3. In FIG. 9A, the target trajectory in the state X1 is indicated by the solid-line curve, the target trajectory in the state X2 by the dot-and-dash-line curve, and the target trajectory in the state X3 by the broken-line curve. As described hereinbefore, since the thermal load on the treatment target is smaller in the state X1 than in the state X2, the rate real of increase of the output voltage V set in the state X1 is smaller than the rate ηa2 of increase of the output voltage V set in the state X2. Therefore, at each point of time until the output time Q of the high-frequency electric power P reaches the threshold value Qth, i.e., Qth0 according to the present modification, the value on the target trajectory set in the state X1 is smaller than the value on the target trajectory set in the state X2. Furthermore, since the thermal load on the treatment target is larger in the state X3 than in the state X2, the rate ηa3 of increase of the output voltage V set in the state X3 is larger than the rate ηa2 of increase of the output voltage V set in the state X2. Therefore, at each point of time until the output time Q of the high-frequency electric power P reaches the threshold value Qth, the value on the target trajectory set in the state X3 is larger than the value on the target trajectory set in the state X2.

According to the present modification, as the rate ηa of increase of the output voltage V as a target value and the target trajectory for the output voltage V are set based on the parameter, i.e., either one of α, P′p, Y, γ, ε, and W′, the rate ηa of increase is set to an appropriate value corresponding to the state of the treatment target and the target trajectory for the output voltage V is set to an appropriate trajectory corresponding to the state of the treatment target. Consequently, when the output from the high-frequency power supply 31 is controlled based on the set rate ηa of increase of the output voltage V and the set target trajectory, the appropriate output is produced from the high-frequency power supply 31 depending on the state of the treatment target, applying the appropriate high-frequency current to the treatment target depending on the state of the treatment target, also according to the present modification.

According to a modification, the processor 25 sets a chronological rate ηa of increase, i.e., rate of change, of the output voltage V according to the target trajectory to a fixed value ηa0 regardless of the detected parameter, i.e., either one of α, P′p, Y, γ, ε, and W′. Therefore, the gradient of the target trajectory for the output voltage V does not vary depending on the parameter, i.e., either one of α, P′p, Y, γ, ε, and W′. Here, there is defined a value, i.e., a starting point value, Vst of the output voltage V at the starting point of the target trajectory upon the start of the output from the high-frequency power supply 31 based on the target trajectory. According to the present modification, the processor 25 sets the value Vst of the output voltage V at the starting point of the target trajectory as a target value for the output control process for controlling the output from the high-frequency power supply 31, based on the detected parameter, i.e., either one of α, P′p, Y, γ, ε, and W′, instead of carrying out the processing of step S105. Then, the processor 25 sets the target trajectory for the output voltage V in the output control process for controlling the output from the high-frequency power supply 31, based on the set starting point value Vst of the output voltage V, instead of carrying out the processing of step S106. According to the set target trajectory, the output voltage V increases chronologically constantly at the fixed value ηa0 from the set starting point value Vst. Then, the processor 25 controls the output from the high-frequency power supply 31 in a manner to have the output voltage V vary along the target trajectory, instead of carrying out the processing of step S108. According to the present modification, the larger the thermal load on the treatment target, the processor 25 sets the starting point value Vst as a target value to a larger value. Consequently, also according to the present modification, the larger the thermal load on the treatment target, the processor 25 sets the value of the output voltage V on the target trajectory to a larger value at each point of time.

FIG. 9B illustrates an example of target trajectories set for the output voltage V from the high-frequency power supply 31 when the temperature T of the heater 23 changes chronologically as illustrated in FIG. 4 according to the present modification. In FIG. 9B, a horizontal axis represents time t from the start, used as a reference, of the output from the heater power supply 41, and a vertical axis the output voltage V from the high-frequency power supply 31. FIG. 9B illustrates the target trajectories in the above three states, i.e., tissue states, X1 through X3. In FIG. 9B, the target trajectory in the state X1 is indicated by the solid-line curve, the target trajectory in the state X2 by the dot-and-dash-line curve, and the target trajectory in the state X3 by the broken-line curve. As described hereinbefore, since the thermal load on the treatment target is smaller in the state X1 than in the state X2, the value Vst1 of the output voltage V at the starting point of the target trajectory set in the state X1 is smaller than the value Vst2 of the output voltage V at the starting point of the target trajectory set in the state X2. Therefore, at each point of time until the output time Q of the high-frequency electric power P reaches the threshold value Qth, i.e., Qth0 according to the present modification, the value on the target trajectory set in the state X1 is smaller than the value on the target trajectory set in the state X2. Furthermore, since the thermal load on the treatment target is larger in the state X3 than in the state X2, the value Vst3 of the output voltage V at the starting point of the target trajectory set in the state X3 is larger than the value, i.e., the starting point value, Vst2 of the output voltage V at the starting point of the target trajectory set in the state X2. Therefore, at each point of time until the output time Q of the high-frequency electric power P reaches the threshold value Qth, the value on the target trajectory set in the state X3 is larger than the value on the target trajectory set in the state X2. According to another modification, the processor 25 sets both the rate ηa of increase of the output voltage V and the starting point value Vst of the output voltage V at the starting point of the target trajectory as target values, based on the detected parameter, i.e., either one of α, P′p, Y, γ, ε, and W′. Also in this case, the larger the thermal load on the treatment target, the processor 25 sets the rate ηa of increase to a larger value and sets the gradient of the target trajectory for the output voltage V to a larger value. Moreover, the larger the thermal load on the treatment target, the processor 25 sets the starting point value Vst of the output voltage V at the starting point of the target trajectory to a larger value.

Second Embodiment

A second embodiment of the present disclosure will be described below with reference to FIGS. 10 through 15. According to the second embodiment, the processing according to the first embodiment is modified as described below. Those parts of the second embodiment which are identical to those of the first embodiment are denoted by identical numeral reference, and will not be described below.

FIG. 10 is a flowchart of a processing sequence carried out by a processor 25 of an energy source apparatus 3 according to the present embodiment. According to the present embodiment, as illustrated in FIG. 10, the processor 25 determines whether or not an operation is entered through an operating member such as a foot switch 18 or the like (S111). If an operation is entered (S111—Yes), then the processor 25 causes the high-frequency power supply 31 to output the high-frequency electric power P at a constant electric power value P0 (S112), and performs a PID control process on the output from the heater power supply 41 (S113), as with the embodiment described hereinbefore, etc. According to the present embodiment, the processor 25 determines whether or not time t from the start, used as a reference, of the output from the heater power supply 41 is equal to or larger than time ta at a first point of time (S114). If time t is shorter than time ta (S114—No), then processing goes back to step S112. Then, the steps from S112 are successively carried out. In other words, up to the first point of time (ta), the processor 25 causes the high-frequency power supply 31 to output the high-frequency electric power P at the electric power value P0, and performs the PID control process for the target temperature T0 on the output from the heater power supply 41.

If time t is equal to or larger than time ta (S114—Yes), then the processor 25 detects an integrated value W′a of the heater electric power P′ from the start of the output from the heater power supply 41 to the first point of time (ta) as a parameter related to the output to the heater 23 (S115). According to the present embodiment, the integrated value W′ a is used as a first parameter detected at the first point of time (ta). As described hereinbefore, the integrated value W′a varies depending on the state of the treatment target including the thermal load on the treatment target. Now, there is defined a second point of time (tb) subsequent to the first point of time (ta). According to the present embodiment, each of times ta and tb is of a fixed value. According to the present embodiment, the processor 25 sets a rate ηb of chronological change, i.e., a rate of increase according to the present embodiment, of the output voltage V as a target value related to the output control process for controlling the output from the high-frequency power supply 31 to the electrodes 21 and 22 from the first point of time (ta) to the second point of time (tb), based on the integrated value W′a detected as the first parameter (S116). Moreover, the processor 25 sets a target trajectory for the output voltage V in the output control process for controlling the output to the electrodes 21 and 22 from the first point of time (ta) to the second point of time (tb), based on the set rate ηb of change (S116). At this time, the target trajectory is set such that the output voltage V increases chronologically constantly at the set rate ηb of change. According to the present embodiment, the larger the integrated value W′ of the heater electric power P′, the processor 25 sets the rate ηb of change of the output voltage V to a larger value. Consequently, the larger the integrated value, i.e., the first parameter, W′a, the processor 25 sets the value on the trajectory value at each point of time from the first point of time (ta) to the second point of time (tb) to a larger value.

Even after the integrated value W′a has been calculated and the rate ηb of change of the output voltage V and the target trajectory have been set, the processor 25 performs the above PID control process for the target temperature T0 on the output from the heater power supply 41 to the heater 23 (S117). After the rate ηb of change of the output voltage V and the target trajectory have been set, the processor 25 controls the output to the electrodes 21 and 22 in a manner to have the output voltage V vary chronologically along the target trajectory for the set rate ηb of change (S118). At this time, the treatment target is modified by the high-frequency current applied thereto. According to the present embodiment, the processor 25 determines whether or not time t is equal to or larger than time tb at the second point of time (S119). If time t is shorter than time tb (S119—No), then processing goes back to S117. Then, the steps from S117 are successively carried out. In other words, up to the second point of time (tb), the processor 25 carries out the output control process on the output from the high-frequency power supply 31 based on the target trajectory for the output voltage V, and carries out the PID control process for the target temperature T0 on the output from the heater power supply 41.

If time t is equal to or larger than time tb (S119—Yes), then the processor 25 detects an integrated value W′b of the heater electric power P′ from the first point of time (ta) to the second point of time (tb) as a parameter related to the output to the heater 23 (S120). According to the present embodiment, the integrated value W′b is used as a second parameter detected at the second point of time (tb). As described hereinbefore, the integrated value W′b varies depending on the state of the treatment target including the thermal load on the treatment target. According to the present embodiment, the processor 25 sets a voltage value Vb of the output voltage V as a target value for the output control process for controlling the output from the high-frequency power supply 31 to the electrodes 21 and 22 after the second point of time (tb), based on the integrated value W′b detected as the second parameter (S121). According to the present embodiment, the larger the integrated value W′b of the heater electric power P′, the larger the voltage value Vb of the output voltage V is set.

Even after the integrated value W′b has been calculated and the voltage value Vb of the output voltage V has been set, the processor 25 performs the above PID control process for the target temperature T0 on the output from the heater power supply 41 to the heater 23 (S122). After the voltage value Vb of the output voltage V has been set, the processor 25 controls the output to the electrodes 21 and 22 in a manner to make the output voltage V constant chronologically at the set voltage value Vb (S123). In other words, after the second point of time (tb), the constant voltage control process is carried out at the set voltage value Vb. At this time, the treatment target is modified by the high-frequency current applied thereto. Then, as with the embodiment described hereinbefore, etc., the processor 25 determines whether or not the output time Q of the high-frequency electric power P is equal to or larger than the threshold value Qth (S124). If the output time Q of the high-frequency electric power P is shorter than the threshold value Qth (S124—Yes), then processing goes back to S122. Then, the steps from S122 are successively carried out. Therefore, until the output time Q reaches the threshold value Qth, the processor 25 continues the constant voltage control process for the set voltage value Vb on the output from the high-frequency power supply 31, continuously modifying the treatment target with the high-frequency current applied thereto. If the output time Q is equal to or larger than the threshold value Qth (S124—Yes), then the processor 25 stops the output from the high-frequency power supply 31 to the electrodes 21 and 22 (S125), as with the embodiment described hereinbefore, etc.

Each of FIGS. 11 and 12 illustrates an example of chronological changes in the heater electric power P′ output from the heater power supply 41 to the heater 23 in the processing sequence carried out by the processor 25. FIG. 13 illustrates an example of target trajectories set for the output voltage V from the high-frequency power supply 31 when the heater electric power P′ changes chronologically as illustrated in FIG. 11. FIG. 14 illustrates an example of target trajectories set for the output voltage V from the high-frequency power supply 31 when the heater electric power P′ changes chronologically as illustrated in FIG. 12. FIG. 15 illustrates an example of chronological changes in the impedance of the treatment target between the first point of time and the second point of time. In each of FIGS. 11 through 15, a horizontal axis represents time t from the start, used as a reference, of the output from the heater power supply 41. In each of FIGS. 11 and 12, a vertical axis represents the heater electric power P′. In each of FIGS. 13 and 14, a vertical axis represents the output voltage V from the high-frequency power supply 31. In FIG. 15, a vertical axis represents the impedance Z. FIGS. 11 and 13 illustrate the chronological changes in the above three states, i.e., tissue states, X1 through X3. In FIGS. 11 and 13, the chronological changes in the state X1 are indicated by the solid-line curve, the chronological changes in the state X2 by the dot-and-dash-line curve, and the chronological changes in the state X3 by the broken-line curve. FIGS. 12 and 14 illustrate the chronological changes in the above state X2 and a state X4 that is different from the states X1 through X3. In FIGS. 12 and 14, the chronological changes in the state X2 are indicated by the dot-and-dash-line curve, and the chronological changes in the state X4 by the solid-line curve. In the state X4, the thermal load on the treatment target at an initial time such as the start of the output from the heater power supply 41 is substantially the same as in the state X2. In the state X4, however, a liquid flows into the treatment target and nearby regions, causing disturbance after the first point of time (ta), for example. The disturbance that is caused increases the thermal load on the treatment target in the state X4. In FIG. 15, the chronological changes in the state X2 are indicated by the dot-and-dash-line curve.

According to the present embodiment, since the PID control process for the target temperature T0 is also carried out on the output from the heater power supply 41, the temperature T of the heater 23 and the heater electric power P′ change chronologically in the same manner as the embodiment described hereinbefore, etc. Therefore, the chronological changes in the heater electric power P′ in each of the states X1 through X3 are the same as the embodiment described hereinbefore. Each of the rate α of rise of the temperature T, the peak electric power P′p, the integrated value W′ of the heater electric power P′, the time Y required for the heater electric power P′ to reach the peak electric power P′p, the rate γ of increase up to the peak electric power P′p, and the rate ε of reduction of the heater electric power P′ after having reached the peak electric power P′p changes depending on the thermal load on the treatment target in the same manner as the embodiment described hereinbefore, etc. In each of the states X1 through X3, the heater electric power P′ becomes the peak electric power P′p between the first point of time (ta) and the second point of time (tb).

In the state X4, until the first point of time (ta), i.e., until disturbance is caused, the temperature T and the heater electric power P′ change chronologically as in the state X2. Actually, the integrated value W′a4 of the heater electric power P′ from the start of the output thereof to the first point of time (ta) in the state X4 is substantially identical to the integrated value W′ a2 of the heater electric power P′ from the start of the output thereof to the first point of time (ta) in the state X2. However, in the state X4, disturbance is caused after the first point of time (ta) and before the second point of time (tb), resulting in an increase in the thermal load on the treatment target. In the state X4, because of the disturbance caused, the rate α of rise of the temperature T up to the target temperature T0 decreases after the disturbance has been caused. In the state X4, the peak electric power P′p increases and the time Y required for the heater electric power P′ to reach the peak electric power P′p increases compared to a case where no disturbance is caused. Actually, the peak electric power P′p4 in the state X4 is larger than the peak electric power P′p2 in the state X2, and the time Y4 required for the heater electric power P′ to reach the peak electric power P′p4 in the state X4 is longer than the time Y2 required for the heater electric power P′ to reach the peak electric power P′p2 in the state X2. In the state X4, the heater electric power P′ becomes the peak electric power P′p between the first point of time (ta) and the second point of time (tb).

Since in the state X4, the peak electric power P′p increases compared to the case where no disturbance is caused, the integrated value W′b of the heater electric power P′ from the first point of time (ta) to the second point of time (tb) also increases. Actually, the integrated value W′b4 of the heater electric power P′ from the first point of time (ta) to the second point of time (tb) in the state X4 is larger than the integrated value W′a2 of the heater electric power P′ from the first point of time (ta) to the second point of time (tb) in the state X2. In the state X4, the rate ε of reduction of the heater electric power P′ after having reached the peak electric power P′p decreases and approaches zero compared to the case where no disturbance is caused. In other words, in the state X4, the heater electric power P′ after having reached the peak electric power P′p decreases gradually compared to the case where no disturbance is caused. Actually, the rate ε4 of reduction of the heater electric power P′ in the state X4 is smaller than the rate ε2 of reduction of the heater electric power P′ in the state X2.

Furthermore, the larger the thermal load on the treatment target until the first point of time (ta), the larger the integrated value W′a of the heater electric power P′ as the first parameter. According to the present embodiment, the larger the integrated value W′a, the processor 25 sets the rate ηb of change, i.e., the rate of increase, of the output voltage V from the first point of time (ta) to the second point of time (tb) to a larger value, and sets the value on the target trajectory for the output voltage V to a larger value at each point of time from the first point of time (ta) to the second point of time (tb). Therefore, the larger the thermal load on the treatment target until the first point of time (ta), the larger the rate ηb of change, i.e., the rate of increase, of the output voltage V is set, and the value on the target trajectory where the output voltage V changes at the rate rib of change is set to a larger value. Actually, the rate ηb1 of change in the state X1 is smaller than the rate ηb2 of change in the state X2, and the value on the target trajectory for the output voltage V in the state X1 is smaller than the value on the target trajectory in the state X2. Similarly, the rate ηb3 of change in the state X3 is larger than the rate ηb2 of change in the state X2, and the value on the target trajectory in the state X3 is larger than the value on the target trajectory in the state X2. The rate ηb4 of change in the state X4 is substantially identical to the rate ηb2 of change in the state X2, and the target trajectories from the first point of time (ta) to the second point of time (tb) are substantially identical to each other in the states X2 and X4.

According to the present embodiment, from the first point of time (ta) to the second point of time (tb), the output from the high-frequency power supply 31 is controlled based on the target trajectory with the set rate ηb of change. Therefore, the larger the thermal load on the treatment target until the first point of time (ta), the higher the output from the high-frequency power supply 31 from the first point of time (ta) to the second point of time (tb), resulting in a larger high-frequency current applied to the treatment target.

Since the output from the high-frequency power supply 31 is controlled based on the target trajectory from the first point of time (ta) to the second point of time (tb), a high-frequency current is applied to the treatment target. From the first point of time (ta) to the second point of time (tb), the treatment target is dehydrated due to the heat caused by the high-frequency current, with the result that the impedance Z of the treatment target varies. According to the present embodiment, as the impedance Z varies, the impedance Z takes a minimum value Zmin between the first point of time (ta) and the second point of time (tb). At the time the impedance Z takes the minimum value Zmin, the impedance Z switches from a chronologically decreasing state to a chronologically increasing state. In FIG. 15, only the impedance Z in the state X2 is illustrated. However, in each of the states X1, X3, and X4, the impedance Z also takes a minimum value Zmin between the first point of time (ta) and the second point of time (tb).

The larger the thermal load on the treatment target from the first point of time (ta) to the second point of time (tb), the larger the integrated value W′b of the heater electric power P′ as the second parameter. According to the present embodiment, the larger the integrated value W′b, the processor 25 sets the voltage value Vb of the output voltage V after the second point of time (tb) to a larger value. Consequently, the larger the thermal load on the treatment target from the first point of time (ta) to the second point of time (tb), the larger the voltage value Vb of the output voltage V in the constant voltage control process is set. Actually, the voltage value Vb1 in the state X1 is smaller than the voltage value Vb2 in the state X2. Similarly, the voltage value Vb3 in the state X3 is larger than the voltage value Vb2 in the state X2. In the state X4, the thermal load on the treatment target from the first point of time (ta) to the second point of time (tb) increases due to disturbance caused. Therefore, the voltage value Vb4 in the state X4 is larger than the voltage value Vb2 in the state X2.

According to the present embodiment, after the second point of time (tb), the constant voltage control process is performed on the output from the high-frequency power supply 31 based on the voltage value Vb set as the target value. Therefore, the larger the thermal load on the treatment target from the first point of time (ta) to the second point of time (tb), the higher the output from the high-frequency power supply 31 after the second point of time (tb), resulting in a larger high-frequency current applied to the treatment target. The thermal load on the treatment target increases from the first point of time (ta) to the second point of time (tb) due to disturbance caused. Consequently, in the state X4, the output from the high-frequency power supply 31 after the second point of time (tb) is high, and a large high-frequency current is applied to the treatment target after the second point of time (tb) compared to the state X2 where no disturbance occurs.

Inasmuch as the processor 25 performs its processing sequence described hereinbefore, the present embodiment operates in the same manner and offers the same advantages as the embodiment described hereinbefore, etc. Furthermore, according to the present embodiment, even if disturbance is caused after the start of the output from the heater power supply 41 and the thermal load on the treatment target is increased by the disturbance, the increase in the thermal load due to the disturbance is appropriately detected. After the second point of time (tb), a target value and/or a target trajectory is set for the output control process for controlling the output from the high-frequency power supply 31 depending on the increase in the thermal load due to the disturbance caused. Therefore, even in the event of disturbance caused after the start of the output from the heater power supply 41, an output is appropriately produced from the high-frequency power supply 31 depending on the increase in the thermal load due to the disturbance caused, and a high-frequency current is appropriately applied to the treatment target depending on the increase in the thermal load due to the disturbance caused.

Modifications of the Second Embodiment

FIG. 16 illustrates an example of target trajectories set for the output voltage V from the high-frequency power supply 31 when the heater electric power P′ changes chronologically as illustrated in FIG. 11 according to a modification. In FIG. 16, a horizontal axis represents time t from the start, used as a reference, of the output from the heater power supply 41, and a vertical axis the output voltage V. FIG. 16 illustrates the target trajectories in the above three states, i.e., tissue states, X1 through X3. In FIG. 16, the target trajectory in the state X1 is indicated by the solid-line curve, the target trajectory in the state X2 by the dot-and-dash-line curve, and the target trajectory in the state X3 by the broken-line curve.

According to the present modification, at the first point of time (ta), the processor 25 sets a rate ηc of chronological change of the output voltage V based on the integrated value W′a. Then, the processor 25 sets a target trajectory where the output voltage V changes chronologically constantly at the set rate ηc of change between the first point of time (ta) and the second point of time (tb). From the first point of time (ta) to the second point of time (tb), the output from the high-frequency power supply 31 is controlled to have the output voltage V vary along the target trajectory. According to the present modification, the larger the thermal load on the treatment target until the first point of time (ta), the larger the rate ηc of change is set, and the larger the value on the target trajectory is set. According to the present modification, however, the processor 25 can set the rate ηc of change to a positive value, zero, or a negative value. For example, in the state X1 where the thermal load is small, the rate ηc1 of change is set to a negative value. Therefore, according to the target trajectory for the output voltage V set from the first point of time (ta) to the second point of time (tb) in the state X1, the output voltage V decreases chronologically at a constant rate of change, i.e., a rate of reduction.

According to the present modification, at the second point of time (tb), the processor 25 sets a voltage value Vc of the output voltage V based on the integrated value W′b. According to the present modification, the larger the thermal load on the treatment target from the first point of time (ta) to the second point of time (tb), the larger the voltage value Vc is set. After the second point of time (tb), the processor 25 controls the output from the high-frequency power supply 31 based on the set voltage value Vc. According to the present modification, however, the processor 25 does not instantaneously change the output voltage V to the set voltage value Vc at the second point of time (tb) or immediately thereafter. According to the present modification, the processor 25 controls the output from the high-frequency power supply 31 to have the output voltage V approach the set voltage value Vc gradually until some time elapses from the second point of time (tb). Then, at a point of time tc when some time has elapsed from the second point of time (tb), the processor 25 controls the output voltage V to reach the set voltage value Vc. After the point of time tc, the processor 25 performs a constant voltage control process for chronologically maintaining the output voltage V at the set voltage value Vc.

In the embodiment described hereinbefore, the target values, i.e., ηb, ηc, etc., and/or the target trajectory from the first point of time (ta) to the second point of time (tb) is set based on the integrated value W′a, and the target values, i.e., Vb, Vc, etc., and/or the target trajectory after the second point of time (tb) is set based on the integrated value W′b. However, the present disclosure is not limited to such details. According to a modification, the target values, i.e., ηb, ηc, etc., and/or the target trajectory from the first point of time (ta) to the second point of time (tb) is set based on the rate γ of increase of the heater electric power P′ at the first point of time (ta). Moreover, the target values, i.e., Vb, Vc, etc., and/or the target trajectory after the second point of time (tb) is set based on the rate ε of reduction of the heater electric power P′ at the second point of time (tb). Specifically, at the first point of time (ta), the target values, i.e., ηb, ηc, etc., and/or the target trajectory from the first point of time (ta) to the second point of time (tb) may be set based on either one of the above parameters, i.e., α, P′p, Y, γ, ε, W′, etc. Furthermore, at the second point of time (tb), the target values, i.e., Vb, Vc, etc., and/or the target trajectory after the second point of time (tb) may be set based on either one of the above parameters, i.e., α, P′p, Y, γ, ε, W′, etc.

In the embodiment described hereinbefore, etc., time ta at the first point of time and time tb at the second point of time are of fixed values. However, the present disclosure is not limited to such details. According to a modification, the initial value Ze of the impedance Z is detected at the same time as or immediately after the start of the output from the high-frequency power supply 31. Then, the processor 25 sets the first point of time (ta) based on the detected initial value Ze of the impedance Z. According to a modification, after the first point of time (ta), the processor 25 performs the above process of detecting the minimum value Zmin of the impedance Z. Then, the processor 25 sets the point of time when it detects that the impedance Z takes the minimum value Zmin, as the second point of time (tb). The minimum value Zmin is detected according to a known process. The point of time when the minimum value Zmin is detected, i.e., the set second point of time (tb), is after the point of time when the impedance Z takes the minimum value Zmin.

Other Modifications

In the embodiment described hereinbefore, etc., the threshold value Qth for the output time Q that is used to determine whether to stop the output from the high-frequency power supply 31 is of a fixed value Qth0. However, the present disclosure is not limited to such details. According to a modification, the processor 25 sets the threshold value Qth for the output time Q based on the detected parameter, i.e., either one of α, P′p, Y, γ, ε, and W′. Then, the processor 25 stops the output from the high-frequency power supply 31 when a predetermined condition based on the set threshold value Qth is satisfied. If the magnitude of the detected parameter, i.e., either one of α, P′p, Y, γ, ε, and W′, is different, then the time for which the output is produced from the high-frequency power supply 31 is different, and the time for which the high-frequency current is applied to the treatment target is different. The larger the thermal load on the treatment target, the larger the threshold value Qth for the output time Q is set. Consequently, in case the rate α of rise of the temperature T is to be detected as a parameter related to the temperature T, the smaller the rate α of rise, the processor 25 sets the threshold value Qth to a larger value.

According to a modification, the processor 25 may determine whether to stop the output from the high-frequency power supply 31 based on the threshold value Zth for the impedance Z, instead of carrying out the processing of S109 or S124 that uses the threshold value Qth for the output time Q. According to the present modification, the processor 25 may set the threshold value Zth to a fixed value Zth0 regardless of the detected parameter, i.e., either one of α, P′p, Y, γ, ε, and W′, or may the threshold value Zth based on the detected parameter, i.e., either one of α, P′p, Y, γ, ε, and W′. In case the threshold value Zth is to be set based on the parameter, i.e., either one of α, P′p, Y, γ, ε, and W′, the larger the thermal load on the treatment target, the processor 25 sets the threshold value Zth to a larger value. For example, in case the rate α of rise of the temperature T is to be detected as a parameter related to the temperature T, the smaller the rate α of rise, the processor 25 sets the threshold value Zth to a larger value.

According to the present modification, if the impedance Z is smaller than the threshold value Zth, then the processor 25 continuously performs a process similar to the processing of S106 or S107 or a process similar to the processing of S122 or S123 to continue the output to the electrodes 21 and 22, thereby continuously modifying the treatment target by applying the high-frequency current thereto. Therefore, until the impedance Z reaches the threshold value Zth, i.e., until a condition based on the threshold value Zth is satisfied, the processor 25 continues the output from the high-frequency power supply 31 to the electrodes, i.e., bipolar electrodes 21 and 22. If the impedance Z is equal to or larger than the threshold value Zth, then the processor 25 performs a process similar to S110 or S125 to stop the output from the high-frequency power supply 31 to the electrodes 21 and 22.

In the embodiment described hereinbefore, etc., the output from the high-frequency power supply 31 is started at the same time as or immediately after the start of the output from the heater power supply 41, and the high-frequency power supply 31 outputs the high-frequency electric power P before the parameter, i.e., either one of α, P′p, Y, γ, ε, and W′, is detected for the first time. However, the present disclosure is not limited to such details. According to a modification, the processor 25 may start the output to the electrodes 21 and 22 after having started the output to the heater 23 and having detected the parameter, i.e., either one of α, P′p, Y, γ, ε, and W′, for the first time. In this case, the processor 25 keeps stopping the output from the high-frequency power supply 31, instead of performing the processing of S102 or S112. According to the present modification, the target values, i.e., β, Va, Pa, Ia, ηa, Vst, ηb, Vb, ηc, Vc, etc., and/or the target trajectory related to the output control process for controlling the output from the high-frequency power supply 31 is set based on the parameter, i.e., either one of α, P′p, Y, γ, ε, and W′. When the output from the high-frequency power supply 31 is started, the output from the high-frequency power supply 31 is controlled based on the set target values, i.e., β, Va, Pa, Ia, ηa, Vst, ηb, Vb, ηc, Vc, etc., and/or the target trajectory, and the treatment target is modified by the high-frequency current applied thereto.

In the embodiment described hereinbefore, etc., the output from the high-frequency power supply 31 is stopped when a predetermined condition based on the threshold value Qth for the output time Q or the threshold value Zth for the impedance Z is satisfied. However, the present disclosure is not limited to such details. According to a modification, when the above predetermined condition based on the threshold value Qth for the output time Q or the threshold value Zth for the impedance Z is satisfied, the processor 25 lowers the output from the high-frequency power supply 31, reducing the high-frequency current flowing through the treatment target to such an extent that the treatment target will not be modified. According to the present modification, the processor 25 stops the output from the high-frequency power supply 31 upon elapse of a certain time from the reduction of the output to the electrodes 21 and 22 or an operation made by the surgeon or the like.

In the embodiments described hereinbefore, etc., the energy output source 31 or 41 of the energy source apparatus 3 outputs high-frequency electric power P to the bipolar electrodes 21 and 22 thereby causing a high-frequency current to flow through the treatment target between the bipolar electrodes 21 and 22, and outputs heater electric power P′ to the heater 23 thereby causing the heater 23 to generate heat. The processor 25 performs the output control process on the output to the heater 23 to cause the heater 23 to reach the target temperature T0 and to maintain the heater 23 at the target temperature T0, and detects the parameter, i.e., α; P′p; Y; γ; ε; or W′ related to at least one of the temperature T of the heater 23 and the output to the heater 23 in the output control process based on the target temperature T0. Then, the processor 25 sets at least one of the target values, i.e., β, Va, Pa, Ia, ηa, Vst, ηb, Vb, ηc, Vc, etc., and the target trajectory related to the output control process for controlling the output to the bipolar electrodes 21 and 22 while the treatment target is being modified by the high-frequency current applied thereto, based on the detected parameter, i.e., α; P′p; Y; γ; ε; or W′.

The technology disclosed herein is not limited to the embodiments described hereinbefore, but various modifications may be made therein without departing from the scope of the disclosure when it is reduced to practice. The embodiments may be appropriately combined as much as possible, and the combinations offer combined advantages. Furthermore, the embodiments include disclosures in various stages, and various disclosures can be extracted by appropriately combining a plurality of components that are disclosed.

One aspect of the disclosed technology is directed to an energy source apparatus used in a treatment tool having a heater and bipolar electrodes. The energy source apparatus comprises an energy output source configured to output high-frequency electric power to the bipolar electrodes through a first circuit. A high-frequency current flowing through a treatment target between the bipolar electrodes. The energy output source is configured to output heater electric power to the heater for generating heat through a second circuit. At least one processor is configured to control the energy output source. The processor is configured to control the heater for reaching a target temperature while maintaining the heater at the target temperature. The processor detects a parameter calculated based on the second circuit during the process of controlling the heater for reaching the target temperature and set a target value and/or a target trajectory for outputting the high-frequency electric power based on the parameter.

The processor is configured to start outputting the high-frequency electric power to the bipolar electrodes after outputting the heater electric power and detecting the parameter. The processor controls the high-frequency electric power to the bipolar electrodes based on the target value and/or the target trajectory and modifies the treatment target by applying the high-frequency current thereto. The smaller the parameter, the processor sets the target value to a larger value and/or sets at least one of a gradient of the target trajectory and a value at the starting point of the target trajectory to a larger value. The processor is configured to detect a rate of increase of the temperature of the heater until the target temperature is reached as the parameter. The larger the parameter, the processor sets the target value to a larger value and/or sets at least one of a gradient of the target trajectory and a value at the starting point of the target trajectory to a larger value. The processor is configured to detect at least one of peak electric power of the heater electric power output to the heater, a time required for the heater electric power to reach the peak electric power, a rate of increase of the heater electric power until the peak electric power is reached, a rate of reduction of the heater electric power after the peak electric power is reached, and an integrated value of the heater electric power as the parameter.

The processor is configured to set the target value and/or the target trajectory with respect to at least one of the high-frequency electric power output to the bipolar electrodes. The high frequency current output to the bipolar electrodes, a voltage output to the bipolar electrodes, and an impedance of the treatment target. The parameter includes a first parameter and a second parameter. The processor is configured to detect the first parameter at a first point of time, to detect the second parameter at a second point of time after the first point of time, and to set the target value and/or the target trajectory from the first point of time to the second point of time based on the first parameter and set the target value and/or the target trajectory after the second point of time based on the second parameter. The processor is configured to control the high-frequency electric power to the bipolar electrodes based on the target value and/or the target trajectory to modify the treatment target with the high-frequency current applied thereto to thereby minimizing an impedance of the treatment target between the first point of time and the second point of time. The processor is configured to control the energy output source such that the larger a thermal load being applied on the treatment target, the larger the high-frequency current flows through the treatment target. The processor is configured to detect the parameter calculated based on the second circuit during the process of controlling the heater for reaching the target temperature. The parameter is related to a temperature of the heater and/or an output from the heater electric power and set the target value and/or the target trajectory for outputting the high-frequency electric power based on the parameter while the treatment target is being modified by the high-frequency current applied thereto.

Another aspect of the disclosed technology is directed to a treatment system comprises a treatment tool having a heater and bipolar electrodes to grip a treatment target. An energy source apparatus is used to electrically communicate with the treatment tool. The energy output source is configured to output high-frequency electric power to the bipolar electrodes through a first circuit. A high-frequency current flows through the treatment target between the bipolar electrodes and the energy output source is configured to output heater electric power to the heater for generating heat through a second circuit. At least one processor is used to control the energy output source. At least one processor is configured to control the heater for reaching a target temperature while maintaining the heater at the target temperature. The processor detects a parameter calculated based on the second circuit during the process of controlling the heater for reaching the target temperature and set a target value and/or a target trajectory for outputting the high-frequency electric power based on the parameter.

A further aspect of the disclosed technology is directed to a method of operating a treatment system having a treatment tool including a heater and bipolar electrodes to grip a treatment target and an energy source apparatus used to electrically communicate with the treatment tool. The energy source apparatus comprises at least one processor used to control the energy output source by: outputting high-frequency electric power to the bipolar electrodes through a first circuit, a high-frequency current flowing through the treatment target between the bipolar electrodes, outputting heater electric power to the heater for generating heat through a second circuit, controlling the heater for reaching a target temperature while maintaining the heater at the target temperature, detecting a parameter calculated based on the second circuit during the process of controlling the heater for reaching the target temperature, and setting a target value and/or a target trajectory for outputting a high-frequency electric power based on the parameter while the treatment target is being modified by the high-frequency current applied thereto.

While various embodiments of the disclosed technology have been described above, it should be understood that they have been presented by way of example only, and not of limitation. Likewise, the various diagrams may depict an example schematic or other configuration for the disclosed technology, which is done to aid in understanding the features and functionality that can be included in the disclosed technology. The disclosed technology is not restricted to the illustrated example schematic or configurations, but the desired features can be implemented using a variety of alternative illustrations and configurations. Indeed, it will be apparent to one of skill in the art how alternative functional, logical or physical locations and configurations can be implemented to implement the desired features of the technology disclosed herein.

Although the disclosed technology is described above in terms of various exemplary embodiments and implementations, it should be understood that the various features, aspects and functionality described in one or more of the individual embodiments are not limited in their applicability to the particular embodiment with which they are described, but instead can be applied, alone or in various combinations, to one or more of the other embodiments of the disclosed technology, whether or not such embodiments are described and whether or not such features are presented as being a part of a described embodiment. Thus, the breadth and scope of the technology disclosed herein should not be limited by any of the above-described exemplary embodiments.

Terms and phrases used in this document, and variations thereof, unless otherwise expressly stated, should be construed as open ended as opposed to limiting. As examples of the foregoing: the term “including” should be read as meaning “including, without limitation” or the like; the term “example” is used to provide exemplary instances of the item in discussion, not an exhaustive or limiting list thereof; the terms “a” or “an” should be read as meaning “at least one,” “one or more” or the like; and adjectives such as “conventional,” “traditional,” “normal,” “standard,” “known” and terms of similar meaning should not be construed as limiting the item described to a given time period or to an item available as of a given time, but instead should be read to encompass conventional, traditional, normal, or standard technologies that may be available or known now or at any time in the future. Likewise, where this document refers to technologies that would be apparent or known to one of ordinary skill in the art, such technologies encompass those apparent or known to the skilled artisan now or at any time in the future.

The presence of broadening words and phrases such as “one or more,” “at least,” “but not limited to” or other like phrases in some instances shall not be read to mean that the narrower case is intended or required in instances where such broadening phrases may be absent.

Additionally, the various embodiments set forth herein are described in terms of exemplary schematics, block diagrams, and other illustrations. As will become apparent to one of ordinary skill in the art after reading this document, the illustrated embodiments and their various alternatives can be implemented without confinement to the illustrated examples. For example, block diagrams and their accompanying description should not be construed as mandating a particular configuration. 

What is claimed is:
 1. An energy source apparatus used in a treatment tool having a heater and bipolar electrodes, the energy source apparatus comprising: an energy output source configured to output high-frequency electric power to the bipolar electrodes through a first circuit, a high-frequency current flowing through a treatment target between the bipolar electrodes, and the energy output source configured to output heater electric power to the heater for generating heat through a second circuit; and at least one processor configured to control the energy output source, wherein the processor is configured to control the heater for reaching a target temperature while maintaining the heater at the target temperature, detect a parameter calculated based on the second circuit during the process of controlling the heater for reaching the target temperature, and set a target value and/or a target trajectory for outputting the high-frequency electric power based on the parameter.
 2. The energy source apparatus of claim 1, wherein the processor is configured to start outputting the high-frequency electric power to the bipolar electrodes after outputting the heater electric power and detecting the parameter, control the high-frequency electric power to the bipolar electrodes based on the target value and/or the target trajectory, and modify the treatment target by applying the high-frequency current thereto.
 3. The energy source apparatus of claim 1, wherein the smaller the parameter, the processor sets the target value to a larger value and/or sets at least one of a gradient of the target trajectory and a value at the starting point of the target trajectory to a larger value.
 4. The energy source apparatus of claim 3, wherein the processor is configured to detect a rate of increase of the temperature of the heater until the target temperature is reached as the parameter.
 5. The energy source apparatus of claim 1, wherein the larger the parameter, the processor sets the target value to a larger value and/or sets at least one of a gradient of the target trajectory and a value at the starting point of the target trajectory to a larger value.
 6. The energy source apparatus of claim 5, wherein the processor is configured to detect at least one of peak electric power of the heater electric power output to the heater, a time required for the heater electric power to reach the peak electric power, a rate of increase of the heater electric power until the peak electric power is reached, a rate of reduction of the heater electric power after the peak electric power is reached, and an integrated value of the heater electric power as the parameter.
 7. The energy source apparatus of claim 1, wherein the processor is configured to set the target value and/or the target trajectory with respect to at least one of the high-frequency electric power output to the bipolar electrodes, the high frequency current output to the bipolar electrodes, a voltage output to the bipolar electrodes, and an impedance of the treatment target.
 8. The energy source apparatus of claim 1, wherein the parameter includes a first parameter and a second parameter, the processor is configured to detect the first parameter at a first point of time and the processor is configured to detect the second parameter at a second point of time after the first point of time; and the processor is configured to set the target value and/or the target trajectory from the first point of time to the second point of time based on the first parameter, and set the target value and/or the target trajectory after the second point of time based on the second parameter.
 9. The energy source apparatus of claim 8, wherein the processor is configured to control the high-frequency electric power to the bipolar electrodes based on the target value and/or the target trajectory to modify the treatment target with the high-frequency current applied thereto to thereby minimizing an impedance of the treatment target between the first point of time and the second point of time.
 10. The energy source apparatus of claim 1, wherein the processor is configured to control the energy output source such that the larger a thermal load being applied on the treatment target, the larger the high-frequency current flows through the treatment target.
 11. The energy source apparatus of claim 1, wherein the processor is configured to detect the parameter calculated based on the second circuit during the process of controlling the heater for reaching the target temperature, the parameter being related to a temperature of the heater and/or an output from the heater electric power, set the target value and/or the target trajectory for outputting the high-frequency electric power based on the parameter while the treatment target is being modified by the high-frequency current applied thereto.
 12. A treatment system comprising: a treatment tool having a heater and bipolar electrodes to grip a treatment target; and an energy source apparatus used to electrically communicate with the treatment tool wherein the energy output source configured to output high-frequency electric power to the bipolar electrodes through a first circuit, a high-frequency current flowing through the treatment target between the bipolar electrodes, and the energy output source configured to output heater electric power to the heater for generating heat through a second circuit, and at least one processor used to control the energy output source, wherein the at least one processor is configured to: control the heater for reaching a target temperature while maintaining the heater at the target temperature, detect a parameter calculated based on the second circuit during the process of controlling the heater for reaching the target temperature, and set a target value and/or a target trajectory for outputting the high-frequency electric power based on the parameter.
 13. The treatment system of claim 12, wherein the processor is configured to: start outputting the high-frequency electric power to the bipolar electrodes after outputting the heater electric power and detecting the parameter, control the high-frequency electric power to the bipolar electrodes based on the target value and/or the target trajectory, and modify the treatment target by applying the high-frequency current thereto.
 14. The treatment system of claim 12, wherein the smaller the parameter, the processor sets the target value to a larger value and/or sets at least one of a gradient of the target trajectory and a value at the starting point of the target trajectory to a larger value.
 15. The treatment system of claim 12, wherein the larger the parameter, the processor sets the target value to a larger value and/or sets at least one of a gradient of the target trajectory and a value at the starting point of the target trajectory to a larger value.
 16. The treatment system of claim 12, wherein the processor is configured to set the target value and/or the target trajectory with respect to at least one of the high-frequency electric power output to the bipolar electrodes, a high frequency current output to the bipolar electrodes, a voltage output to the bipolar electrodes, and an impedance of the treatment target.
 17. The treatment system of claim 12, wherein the parameter is defined by respective first and second parameters each of which being detected by the processor at respective first and second point of time and wherein the processor is configured to set the target value and/or the target trajectory from the first point of time to the second point of time based on the first parameter, and set the target value and/or the target trajectory after the second point of time based on the second parameter.
 18. The treatment system of claim 12, wherein the processor is configured to detect the parameter calculated based on the second circuit during the process of controlling the heater for reaching the target temperature, the parameter being related to a temperature of the heater and/or an output from the heater electric power, set the target value and/or the target trajectory for outputting the high-frequency electric power based on the parameter while the treatment target is being modified by the high-frequency current applied thereto.
 19. A method of operating a treatment system having a treatment tool including a heater and bipolar electrodes to grip a treatment target and an energy source apparatus used to electrically communicate with the treatment tool, the energy source apparatus comprising at least one processor used to control the energy output source by: outputting high-frequency electric power to the bipolar electrodes through a first circuit, a high-frequency current flowing through the treatment target between the bipolar electrodes; outputting heater electric power to the heater for generating heat through a second circuit; controlling the heater for reaching a target temperature while maintaining the heater at the target temperature; detecting a parameter calculated based on the second circuit during the process of controlling the heater for reaching the target temperature; and setting a target value and/or a target trajectory for outputting a high-frequency electric power based on the parameter while the treatment target is being modified by the high-frequency current applied thereto.
 20. The method of operating a treatment system of claim 19 wherein the parameter is defined by respective first and second parameters each of which being detected by the processor at respective first and second point of time and wherein the processor is configured to set the target value and/or the target trajectory from the first point of time to the second point of time based on the first parameter, and set the target value and/or the target trajectory after the second point of time based on the second parameter. 